Because Engineering!

Jansen mechanism is a leg mechanism used to mirror a smooth walking motion. It was devised by a kinetic sculptor, Theo James. He has used his mechanism in a variety of kinetic sculptures which are known as Strandbeests. This old man made a bicycle out of wood imitating the Jansen’s mechanism. This GIF shows the people enjoying as he rides his bicycle. You can watch Theo’s Strandbeests here.